The present invention relates to beam compasses for drafting, and specifically relates to inexpensive yet reliable beam compasses.
Beam compasses typically have two implement holders: a writing implement holder for securing a writing implement such as a pencil, and a compass point holder for securing a compass point tool. Reliable beam compasses typically have writing implements and adjustable compass point tools which remain firmly in place during use. If the compass point tool, or the writing implement, were to loosen during use, the compass would be inaccurate and unreliable. As a result of this need for stability, present beam compasses are typically complex and involve a relatively large number of small moving parts. Not only are some of these compasses difficult to use, but they are also expensive to fabricate. The expense is due largely to the number of component parts in each compass as well as the complexity of precision fabrication.
Inexpensive beam compasses typically have fewer components and are thus relatively less expensive to fabricate than expensive beam compasses. Inexpensive beam compasses, however, tend to be unreliable due to the few moving components eventually loosening with respect to one another. For example, adjustable components which move by overcoming a small amount of friction may tend to loosen and separate, and adjustable components which rely on set screws may tend to loosen and wobble.
There is a need therefore for an adjustable beam compass which is reliable yet inexpensive to fabricate.